1. Field of the Invention
This invention relates to a watermark data hiding (embedding) apparatus, a method of hiding (embedding) watermark data, a method of transmitting data including watermark data, a recording medium storing data including watermark data, a (data and) watermark data reading apparatus, and a method of reading data and watermark data.
2. Description of the Prior Art
A digital watermark technique is known. In such a digital watermark technique, watermark data is hidden (embedded) in a redundancy portion of video data or sound data so as not to change the total amount of data, so that the watermark data cannot be detected in the human sensitivity.
The aim of the present invention is to provide a superior watermark data hiding apparatus, a superior method of hiding watermark data, a superior method of transmitting data including watermark data, a superior recording medium storing data including watermark data, and a superior (data and) watermark data reading apparatus, and a superior method of reading data and watermark data.
According to the present invention there is provided a watermark data hiding apparatus including: an error detection code adding circuit for adding error detection codes to watermark data to generate error detection code added watermark data; an encryption circuit for scrambling the error detection code added watermark data in accordance with an inputted password; a plurality of watermark data hiding circuits for hiding the encrypted error detection code added watermark data in the content data by different hiding algorithms, respectively; and a selecting circuit responsive to a selection signal for selecting one of a plurality of the watermark data hiding circuits to output the content data in which the encrypted error detection code added watermark data is hidden by the selected watermark data hiding circuit.
According to the present invention there is provided a method of hiding watermark data in content data including steps of: adding error detection codes to watermark data to generate error detection code added watermark data; encrypting the error detection code added watermark data in accordance with an inputted password; hiding the encrypted error detection code added watermark data in the content data by different hiding algorithms, respectively; and selecting one of different hiding algorithms in response to a selection signal to output the content data in which the encrypted error detection code added watermark data is hidden by the selected one of different hiding algorithms.
The content data in which the encrypted error detection code added watermark data is hidden by one of different hiding algorithms may be transmitted.
According to the present invention there is provided a recording medium including: a substrate; and a data storing layer for storing content data, watermark data, and error detection codes of the watermark data, wherein the error detection codes are added to the watermark data to generate error detection code added watermark data, the error detection code added watermark data is encrypted in accordance with an inputted password; the encrypted error detection code added watermark data is hidden in the content data by different hiding algorithms, respectively, one of different hiding algorithms is selected in response to a selection signal, and the content data in which the encrypted error detection code added watermark data is hidden by the selected one of different hiding algorithms.
According to the present invention there is provided a watermark data reading apparatus, wherein the watermark data is attached with error detection codes, the watermark data and the error detection codes are encrypted in accordance with a first password, the watermark data and the error detection codes are hidden in the content data by the selected one of N hiding algorithms in response to a selection signal to output the content data in which the error detection code and watermark data is hidden by the selected one of N hiding algorithms, N being a natural number more than one, the watermark data reading apparatus including: N decoders for reading watermark data and the error detection codes from the content data by N extracted (inverse-hiding) algorithms corresponding to the N extracting (hiding) algorithms, respectively, to output N inverse-hidden content data including the N read watermark data and the N error detection codes; N decrypting circuits for decrypting the N read watermark data and the N error detection codes from the reading circuit in accordance with a second password corresponding to the first password, respectively; N error detecting circuits for detecting errors in the N error detection codes, respectively; and a selecting circuit for selecting and outputting one of the N inverse-hidden content data in accordance with the errors.
According to the present invention there is provided a method of reading content data and watermark data hidden in the content data, wherein the watermark data is attached with error detection codes, the watermark data and the error detection codes are encrypted in accordance with a first password, the watermark data and the error detection codes are hidden in the content data by N hiding algorithms, respectively; one of N hiding algorithms is selected in response to a selection signal to output the content data in which the error detection code added watermark data is hidden by the one of N hiding algorithms, N being a natural number more than one, the method including the steps of: (a) reading watermark data and the error detection codes from the content data by N extracting (inverse-hiding) algorithms corresponding to the N hiding algorithms, respectively to output N extracted (inverse-hidden) contents data including the N read watermark data and the N error detection codes; (b) decrypting the N read watermark data and the N error detection codes in step (a) in accordance with a second password corresponding to the first password, respectively; (c) detecting errors in the N error detection codes, respectively; and (d) selecting and outputting one of the N inverse-hidden contents data in accordance with errors detected in step (c).